THE LABEL SPF CANNOT BE USED TO ESTIMATE SAFE SUN EXPOSURE TIME

How SPF Testing Fails to Replicate Real Sunlight and its Impact on Your Health

North American consumers should not rely on label claims - whether it is the SPF or claims of UVA and Broad spectrum protection. Most of our brand name sunscreens would not pass European or Australian criteria for UVA-PF (UVA- Protection Factor) and their better standards for Broad Spectrum coverage. Proper and adequate UVA protection may be the most essential property for a sunscreen to actually prevent skin cancer and photoaging. The global market, particularly in North America is dominated by UVB- BIASED sunscreens with inadequate UVA protection, despite label claims saying ‘BROAD SPECTRUM’ UVA/UVB. Even the EWG (Environmental Working Group) recognizes this reality in their 2017 Sunscreen Report. More on this in my next BLOG. 

There are over 25 stakeholder and professional coalitions with Comprehensive Cancer Control (CCC) plans  that publicise a prevention strategy. Language may differ but they all focus on key elements of sun avoidance, never burn or tan from UV exposure, wearing protective clothing with a tight weave, wear UV protective sunglasses, and generously apply a sunscreen with sun protection factor (SPF) 15 or higher and both UVA/UVB protection. Sunscreen use is the weakest link in the protocol. Rising cancer rates show that the current approach has failed and critical analysis argues that ineffective UVB-BIASED sunscreens dominating the N.American market are a driving factor.  Australia where balanced sunscreens using better UVA filters are plenty,  are actually seeing skin cancer rates levelling off or falling in certain provinces. Two landmark studies from Australia show that effective sunscreens applied daily can potentially reduce all forms of skin cancer. In N. America the grim reality is otherwise:

• Skin cancer is now the most common cancer in the United States with the incidence essentially doubling for all skin cancers in 40 years,  and they now account for more than 50% of all human cancers - i.e. skin cancer cases outnumber all other cancers combined. 

• In 2017, over 160,000 Americans are expected to be diagnosed with melanoma, which is the leading cause of cancer death in women ages 25-30 and the second leading cause in women ages 30-35.  In ages 15-29, melanoma is the second most commonly diagnosed cancer. From 1970 to 2009, the incidence of melanoma increased by 8-fold among young women and 4-fold among young men. In the USA, one person dies of melanoma every 54 minutes (almost 10,000/year).  4000 Americans die in a year from Squamous Cell Cancer (SCC) .

Preventing sunburn (early effect) or UVA damage (early and late effects), and damage to the genetic and immune apparatus of the skin is the essence of effective photoprotection. The label SPF is supposed to quantify a sunscreen’s ability to prevent that early sign of sun damage. The SPF as measured by FDA and Health Canada mandated tests give a poor estimate of the sunscreen’s actual performance in sunlight. 

The premise that SPF can be used to plan your exposure time is based on several invalid assumptions. Recent studies confirm that the lab or label SPF is inaccurate, when compared to the real life value obtained in sunlight. The lamp used in calculations for label purposes, only emits 290-400 nm based on the false assumption that the erythema reaction was mediated only by UVR (UVB and UVA). Visible Light (VL at 400-740 nm)) and Infra-red (IR at beyond 740 nm)) could be responsible for up to 20-30 % of the erythema response. Sunlight has more UVA (up to  5X ) than the testing lamp emission. Industry and physicians continue to advise consumers that the SPF can be used to calculate the safe exposure time for protected skin outdoors. We know differently -  fair individuals mostly get sunburned with prolonged outdoor exposure or during tropical vacations, despite using high SPF sunscreens and stringently following all the re-application instructions.   Media reports in 2015-2017 from Consumer Reports, the BBC in the UK, CBS, NBC, and CNN in the USA, have all presented data that up to 50% of brand name sunscreens fail to achieve even 50% of their labelled SPF values. 

Science now confirms this travesty. The label SPF is inaccurate when compared to the real life value obtained in sunlight. A landmark study  presented at the 26th Annual Meeting of The Photomedicine Society (Orlando, Florida, February 2017), showed that  50 commercially available sunscreens with label SPF 50 or more had SPF values of 6-10  when measured in sunlight (Hughes S. and  Cole C.). No wonder, as testing lamp emission spectrum is far removed from that of actual terrestrial radiation, and the intensity used in testing is different from sunlight. The compliance factor also adds another real life problem as most  users apply < than the 2 mg/cm²  as done for the lab test. Scientists also now provide the principles in physics that explain why the SPF test cannot be accurate (Diffey B, Osterwalder U, 2017).  They report that labelled SPF, determined by in vivo assay using a UV solar simulator, overestimates the SPF that would be expected in natural sunlight.  Products labelled SPF50+ may not be able to achieve a protection against sunlight of more than 25-fold., or SPF 25. The popular interpretation of the SPF to mean how much longer skin covered with sunscreen takes to burn in sunlight compared with unprotected skin, can no longer be defended.

Any falsely high SPF reading can be further  manipulated by adding anti-redness agents (similar to aspirin) that artificially increases the MED (Minimal Erythema Dose) used to determine the SPF, for the sunscreen containing these anti-inflammatory chemicals. Sunscreens are replete with SPF boosters- bisabolol, niacinamide, salicylate compounds, and numerous others. This may be very harmful to a consumer. The false (often high SPF 50-100) values distort the reality of what protection to expect. If you are very fair – Type 1- always burns never tans- you may actually burn within 5 minutes with extreme sun exposure. An SPF 30 conveys the impression that it is safe to stay out for up to 150 minutes and SPF 50 for up to 250 minutes. A real life SPF 10 in sunlight means you should multiply your 5 minute burn time by only 10 for a safe 50 minute exposure, then get out the sun or re-apply your sunscreen liberally if you stay out longer. A boosted SPF is falsely elevated by interfering with the biologic endpoint or early warning signal of redness, the first sign of sunburn. It is no longer commensurate to the amount of radiation being prevented from reaching your skin,  but related to delayed redness. You are actually burning but have no way of knowing this as your early warning signal has been blunted. This false sense of security may make you remain outdoors i/o seeking shade. You will experience more sun damage and incur the risks of skin cancer and photoaging. This  is only related to UVB exposure - think of the damage resulting from the more harmful UVA radiation that you are now receiving in high levels, particularly since most N. American sunscreens have inadequate UVA-PF values.

• Use no more than half the label  SPF when calculating your outdoor exposure time, and if you are redhead or extremely fair use a factor of 10.
• It is better to use the other elements of a photoprotection strategy – avoid sun exposure, wear UV protective clothing, wear head gear and UV protective sunglasses etc. - to the extent you can, and use a sunscreen with a safe UVA filter like zinc oxide in adequate concentrations.
• The particle type sunscreens that use zinc oxide, titanium dioxide, encapsulated octinoxate, drometrizole trisiloxane (Mexoryl XL™), terephthalylidene dicamphor sulfonic acid (Ecamsule or Mexoryl SX™),  biscotrizole (MBBT or Tinosorb M™), bemotrizinol (BEMT or Tinosorb S™),  and others are large in size, sit on the skin avoiding any entry into blood and the various attendant risks. Only the first five are available in Canada. Mexoryl XL™ and SX™ are patented to L’Oreal and regrettably are usually combined with undesirable soluble hydrocarbon filters, which should be stringently avoided. All except titanium dioxide and encapsulated octinoxate are UVA filters, and when mixed with other safe UVB filters achieve dispersions of spectral homeostasis (balanced UVA/UVB protection). In this situation where a sunscreen behaves like a neutral density filter, the label SPF may be closer to the Real Life SPF value in sunlight.  Look for products that have > 20% zinc oxide alone, or 15 % with 7.5% titanium dioxide or encapsulated octinoxate. 
• For maximum protection and to avoid all the controversy on hormone disruption and environmental hazards, use only sunscreens  with particle based or large molecular weight filters in the right combination. The high UVA protection achieves that flat balanced protection where the ratio UVA-PF/SPF approaches 1, and the label SPF comes closer to the Real Life value in sunlight. Strictly avoid all small molecular weight soluble hydrocarbon filters – avobenzone, oxybenzone, homosalate, octisalate, octocrylene, regular octinoxate, and 4-methylbenzilidene camphor. All may enter blood and only avobenzone has any UVA attenuation. It still gives a significant UVB bias where up to 30% of UVA between 340-400 nm – the most damaging UV rays are transmitted to your skin.

© Denis K. Dudley MD, October 2017. All rights reserved.

Can Using a Sunscreen Be Worse than Using a Tanning Bed? The Health Implications of a UVB Biased Sunscreen.

The New Study that Shows How a UVB Sunscreen Can Be Worse than a Tanning Bed

The Role of Long Wave UVA in Skin Cancer

There is an unrelenting rise in skin cancer rates in North America with an annual increase around 2-3 % over the past 3 decades. In the UK there was an alarming increase of 40% in the past 4 years. Empirical analysis of global skin cancer rates suggest that rates are levelling off or decreasing in countries with higher UVA-Protection Factor (UVA-PF) levels in sunscreens (2015 Sunscreen Symposium, Florida, September 2015). The compelling evidence for the primary role of UVA - particularly the UVA1 or longwave UVA -  in the genesis of skin cancer – comes from a number of scientific studies over the past 15 years (Halliday 2002, Agar 2004, Noonan 2012, Rünger 2012). This is logical and intuitive as UVA is more abundant than UVB and penetrates deeper into the skin.

The primary objectives of photoprotection  must be to prevent rising rates for skin cancer, reduce health care expenditures for a disease with potentially preventable aspects, and to reduce other effects of UV radiation, like photoaging and immune suppression. The continual 2-3% annual rise in skin cancer rates for North America shows that the current approach has failed. Critical analysis argues that ineffective UVB biased sunscreens are an important contributory factor. Cancer prevention and immune protection  from sunscreens in humans is dependent on protection from UVA and cannot be predicted from the SPF (sun protection factor), more a measure of UVB attenuation.

There is  a logical and evidence-based argument that the exclusive use of balanced sunscreens, which provide spectral homeostasis or uniform protection at every wavelength can reduce cancer rates and photoaging. The current  science confirms that UVB causes direct DNA damage, whereas UVA results in direct DNA damage and indirect effects from ROS (reactive oxygen species), photoimmunosuppression, and disruption of repair mechanisms.  UVB initiates and modulates the damage cycle but UV (particularly UVA1) completes the process. Photoprotection with traditional UVB biased sunscreens with little or no UVA protection must now be abandoned and a new clinical strategy adopted by doctors and as a public health policy.

How Can A UVB Biased Sunscreen Do More Harm than Good?

There is another powerful bit of evidence that implicates the widespread use of UVB-biased sunscreens, with little or no UVA1 protection, in rising skin cancer rates and visible photoaging at younger ages. Daily use of UVB biased sunscreens that dominate the market, exposes the patient to asymmetric UVA1 radiation, similar to a tanning bed. More people develop skin cancer because of tanning than develop lung cancer because of smoking. One indoor UV tanning session increases users’ risk of developing squamous cell carcinoma by 67 percent and basal cell carcinoma by 29 percent. People who first use a tanning bed before age 35 increase their risk for melanoma by 75 percent.  

There is an important  parallel between the asymmetric UVA1 from tanning bed exposure and using a UVB-biased sunscreen, either on vacation or every day. This crucial fact escapes our regulators, most physicians including dermatologists, and the cosmetic industry. 

Vacation exposure over 2 weeks with typical sunscreens for protection could be double the radiation received from 10  eight minute tanning bed exposures. In extreme cases of recreational sun exposure where sunscreens providing suboptimal broad-spectrum protection are used, the UV insult to the skin is likely to result in higher cumulative exposures than commonly employed sunbed practices (Diffey et al).

This occurred to me several years ago but the science and physics was beyond my capability. I kept asking Uli Osterwalder- one of the authors in the study and a friend- about this obvious concern, until they finally did the calculations. It is a computer derived analysis that suggests the wrong sunscreen - UVB-biased - may be more dangerous than tanning bed exposure. Both provide asymmetric UVA radiation to your skin. There is another cautionary aspect to this. The vacation model is more acute and intense but what about everyday exposure if using a UVB-biased sunscreen? Many outdoor occupations reach or exceed the vacation exposure.

If tanning beds cause higher risks for skin cancer, then providing a patient with a UVB biased sunscreen that gives a similar UV radiation profile, relative to the right conditions of exposure and time, should also be considered as an undesirable measure. For doctors involved with rejuvenation, prescribing a balanced sunscreen that gives adequate UVA1 protection is a responsible practice standard. This is an integral part of post treatment care after rejuvenation procedures. Without balanced protection, the patient resumes accelerated photoaging from UVA1 exposure and the  treatment benefit is quickly lost. Repeat treatments will then be required more quickly. 

What Is A Better Alternative?

Adequate but safe UVA1 protection is only attainable with filters like zinc oxide (>20%), zinc oxide (>15%) plus 7.5% titanium dioxide or encapsulated octinoxate, bemotrizinol, and bisoctrizole – insoluble particle type filters with no entry into our bodies. Regrettably,  the last two safe and highly effective insoluble particle filters, have yet to be approved by Health Canada and the FDA, despite their global use in every other country over the past 15 years.

Most UVB-biased sunscreens use the soluble filters that penetrate skin into blood and even tissues like receptors in the brain. The group includes oxybenzone (benzophenone), homosalate, octisalate, octocrylene, non-encapsulated or regular octinoxate, and 4-methyl benzilidene camphor. They are more active in UVB and shortwave UVA (UVA2). Some UVA1 activity comes from avobenzone, another soluble filter that obtains tissue levels. It enters the body and is unstable in sunlight. Most parents and pregnant women are unaware that these filters (used in over 80% of our sunscreens) gain entry to our bodies, reason enough to avoid them.

There is a principle in endocrinology – isoform function – whereby chemicals with the same structure likely bind to the same hormone receptor and generally have the same effects. Hence avobenzone and octisalate very likely exert the same toxic effects as oxybenzone and homosalate, known to be hormone disruptors. Oxybenzone and its structural cousin avobenzone are now the leading causes of photocontact allergy (Warshaw 2012). A 2015 report (Downs et al) confirms other studies over the past decade that oxybenzone washing of sea-bathers is genotoxic, kills larvae of reproducing coral, and converts the planula from a motile to a sessile state by ossification. Oxybenzone found in 65% of our poses a hazard to coral reef conservation and threatens the resiliency of coral reefs to climate change.

Recommendations for Practitioners and Consumers:

You are faced with a simple choice in selecting a safe and effective sunscreen:

·       UVB- biased products with tiny soluble organic filters that give incomplete protection (inadequate UVA1 protection) and are implicated with adverse effects on our health and the environment. They are likely a root cause of rising cancer rates and early photoaging.

·       A balanced or truly broad spectrum sunscreen using insoluble filters, large particles that remain on the skin, have no known adverse effects on human health or the environment, and give you better protection, where the right combination can approach that of textiles and staying out of the sun.

·      Balanced sunscreens using insoluble particle type UV filters with no entry into blood of mother or fetus are safe to use in pregnancy. More egregious to me, is the fact that nearly all physicians fail to advise pregnant women and parents about percutaneous absorption of soluble filters and their possible hormone disrupting and carcinogenic effects. As a former obstetrician, I appreciate the persuasive simplicity that anything safe to use in pregnancy is safe to use for everyone.

Why Current Sunscreens Are Failing the Public

Sunscreens have been in the news lately. I thought that it would be timely to focus this blog on the issues. The EWG has named Neutrogena as the number # 1  sunscreen brand to avoid in their 2015 annual “Hall of Shame” report. It has gone viral. However many other leading brands continue to use the soluble filters that attain tissue levels and are implicated as hormone disruptors and carcinogens. 

These filters include :

• oxybenzone, avobenzone, homosalate, octisalate, octocrylene, 4-methyl benzilidene camphor and regular octinoxate. 

Better and safer particle based insoluble filters include :

• zinc oxide, encapsulated octinoxate,  titanium dioxide, and Tinosorb S and Tinosorb M (still awaiting FDA and Health Canada approval)

Here is an excerpt from the EWG report naming Neutrogena as the number 1 sunscreen to avoid:

“The Environmental Working Group (EWG) has released their 2015 guide to sunscreen, and among the worst brands for sun protection is the number one culprit for toxicity and false advertising, Neutrogena.“Neutrogena’s advertising hype is further from reality than any other major brand we studied. It claims to be the “#1 dermatologist recommended suncare brand, yet all four products highlighted on Neutrogena’s suncare web page rate 7, in the red – worst – zone in our database,” says EWG.  Not only do many Neutrogena sunscreens contain harmful chemicals like oxybenzone and methylisothiazolinone –– but their advertised SPF levels of over 70 have been debunked by the U.S. Food and Drug Administration. According to the federal department, SPF levels max out at about 50. Europe, Australia and Japan have already banned brands from advertising SPF levels over 50. EWG states 80 per cent of Neutrogena sunscreens contain oxybenzone, “a hormone-disrupting sunscreen filter” and 33 per cent contain retinyl palmitate, “a form of vitamin A linked to skin damage”. 

Taking it a Step Further:

What the document does not say is that the entire class of soluble filters – benzophenone, homosalate and others likely have the same effects and that all the leading brands that use these filters are equally harmful. This would include most Johnson and Johnson, L’Oreal, Coppertone, Proctor and Gamble, Banana Boat products, and 85 % of available sunscreens (EWG Hall of Shame 2015). The same filters give UVB biased protection and do not prevent cancer and photoaging. They are likely a factor in rising skin cancer rates. There are a growing list of adverse effects like reproductive problems, autism spectrum disorders and ADHD linked to hormone disruptors that must include soluble sunscreen filters – oxybenzone, avobenzone, homosalate, octisalate, octocrylene and others.  Each person should make their own choice between two classes of sunscreens.  Either choose sunscreens with small molecular weight soluble filters that obtain tissue levels, give incomplete or UVB-biased protection  to prevent sunburn but little protection against skin cancer and photoaging, and probably have harmful effects due to hormone disruption and carcinogenic effects. The alternative is to choose a balanced sunscreen with insoluble particle type filters that remain on the skin,  give you balanced UVB/UVA or better protection, and have no possible adverse effects.

A Word on Recent Controversy:

CBS news just reported a Consumers Report from May 2015 that 11/34 sunscreens failed to achieve their SPF claims at only 16-70% of their labelled value. This mirrors another report from a consumer group in the UK reported on the BBC website that only 1 in 5 consumers in Britain understand that the SPF only predicts UVB or sunburn protection and are aware of  or understand that the Boots-Diffey star system of 1-5 stars is an index of UVA protection and the balance or ratio of UVA/UVB protection. The BBC also reported in May a consumer group testing of Boots and Hawaiian Tropic sunscreens in the UK, showed the majority did not meet their SPF claims. You do not need studies to prove this – just ask most fair-skinned consumers on holiday – most end up with a sunburn despite using the typical brand names and re-applying them every 2-3 hours as instructed. 

SPF values are manipulated by adding anti-inflammatory agents that do not extinct any UV radiation but decrease the redness on skin and mask the biologic marker and first warning signal for injury to the skin. The solar lamps in labs have a sharp fall at 370 nm and a cut-off of 400nm- unlike sunlight where the curve continues to rise. Studies measuring SPF in actual sunlight show that even high SPF sunscreens at 30-100 usually only attain 10-20% of their labelled SPF claims. It was reported at the Annual Photomedicine Meeting in San Francisco this year that as an example Neutrogena Ultra-Sheer SPF 65 had a SPF value of only 10 in sunlight. The MED responses were assessed by luminary dermatologists not a lab technician!

Ways Forward:

We have always said that using SPF, UVA-PF, and CW values to establish the level of protection is the regulatory hurdle to assure adequate sun protection- an SPF of 30-50, a UVA-PF of a minimum 10 for SPF 30 and a minimum of 17 for SPF to meet or exceed the EU criteria of a UVA-PF/SPF ratio >1/3, and a CW of >370 nm as the secondary measure of balanced protection. This should be expressed on a label as a global standard in a very easy and transparent system to understand for sun protection- minimal, medium, high, and very high.

We advocate that sunscreens be UVA dominant with the ratio as close to 1 as possible, given the new studies over the past 10 years that prove UVA is the main factor in cancer and aging. UVB produces superficial injury as a shorter wavelength and lower intensity- it initiates sunburn and the DNA damage cycle, and modulates the process. UVA1 produces deeper DNA injury in the dermis, produces local and systemic inhibition of the immune system, and completes the damage cycle for photoaging and cancer. The majority of mutations in the keratotic basal layer where most cancers arise are UVA fingerprint mutations (not UVB as previously assumed), from hallmark studies over the past decade. UVA does not vary with latitude, or time of day, is present on cloudy days, is 15 X more intense than UVB, penetrates car and window glass, and is a deeper penetrating longer wavelength. It is easier to decrease your UVB exposure than to hide from UVA. Over 40 years it was counter-intuitive for dermatologists to believe that UVB was the main culprit in cancer and photoaging. Most still do. 

The entire protection strategy that includes the use of UVB-biased sunscreens has failed as is evident from rising cancer rates. In N. America rising skin cancer rates are due in part to ineffective sunscreens with partial UV or UVB-biased coverage. 5 million NMSC cases in the USA now cost the health care system 8.1 billion (up from I million in 1987). In the UK skin cancer has shown an alarming increase of 40% in the past 4 years. In Canada rates rise at a steady 2-3% per annum and melanoma was the 2^nd fastest rising cancer in 2014-15. It is now the leading cause of cancer death in girls aged 15-30 years. Balanced UVA dominant sunscreens could reduce skin cancer rates in 4 decades- NMSC by up to 80% and melanoma by up to 55%.

Final Recommendations: 

Until Tinosorb S and Tinosorb M are approved by the FDA and Health Canada, the only filter or combination of filters in N. America that meet the requirements for safety and balanced protection are as follows:

·       Zinc oxide alone, zinc oxide plus titanium dioxide, or zinc oxide plus encapsulated octinoxate are safe among those available here. Mexoryl SX and LX are also molecules that are > the 500 Dalton rule for no percutaneous entry- both are owned by L’Oreal and are never used without other undesirable filters from the soluble group.

·       Any filter has to used after expert consideration of the absorption curve and transmission metrics, the concentration of each filter, and the proper dispersion of actives within inactive ingredients. The Honest Company (Jessica Alba) fiasco demonstrates this. They had a 20%  ZnO but complaints of poor esthetics were an issue. They reduced the ZnO to 9% - no other active. Anyone with a basic knowledge of Photometrics would know that the true SPF or Real Life SPF in sunlight can only be 12-15 maximum. Each filter based on its UVB/UVA2 absorption efficiency has a finite SPF units per 1% concentration. This only provides minimal UVB or sunburn protection for < 1 hour in the full sun for a very fair-skinned person. If it was dispersed poorly this could fall to around 15 minutes- hence all those sunburns seen on mother-baby blogs. At 9% a second primary and safe UVB filter would be required –either titanium dioxide or encapsulated octinoxate in a concentration of 7.5% to attain a true SPF of around 25-28. Zinc oxide at >15 % with 7.5% of either titanium dioxide or encapsulated octinoxate will reach SPF 30 plus and have adequate UVA protection. 

Chart with Theoretical Maximum SPF Units per 1% of Active

Filter	Max. # of SPF Units per 1% of Active
UVB
Octinoxate	2.8
Homosalate	1.5
Titanium Dioxide	2.6
Octisalate	1.6
Oxybenzone	2.3
Octocrylene	2.1
UVA
Avobenzone	1.9
Zinc Oxide	1.6
Tinosorb M	2.2
Tinosorb S	3.1

Simply Zinc™ (CyberDERM) with 22% gives the best balanced protection and Every Morning Sun Whip ™ is not far behind. We believe both are the most esthetic zinc oxide sunscreens found anywhere. Consumers love the products knowing they are safe even for pregnancy and give maximal protection. My dermatologist wife needed a sunscreen to actually prevent skin cancer and photoaging, and as a high risk obstetrician, I needed to know filters did not pass into maternal blood and reach the fetus. A safe, effective, and esthetic sunscreen was hard to find, so we made our own.

Finally, at the World Congress in Dermatology, we learned that there may be evidence that the soluble filters are also photocarcinogenic and induce skin cancer in susceptible subjects- another reason for soluble filters to be banned under The Precautionary Principle. Imagine how egregious it is that a product could cause the disease it is supposed to prevent.  However, I am not optimistic that anything will change. Finally, several of the soluble filters – octinoxate, avobenzone and octocrylene can be encapsulated that converts them to larger size, so they behave like insoluble particles and become safe. We use encapsulated octinoxate in one sunscreen. The silica capsule is inert and the molecule now sits on the skin like zinc oxide and attains the same safety profile. Encapsulation increases the size from 0.5 nm to 7 microns- larger by about 14,000 times. Industry inexplicably ignores this technology that would make some of the offending filters safe.       

                                                                            

© Denis K. Dudley MD 2015. All Rights reserved.